The dependence of micellar rate effects upon reaction mechanism

“…This interaction could be promoted by the hydrophobic effect of the four-methyl groups of the surfactant head, which displace some solvation water. 37 The action of light in a composition like the one described before, could promote their transfer from the surfactant to the 4-CP intermediaries.…”

Section: Microemulsionsmentioning

confidence: 99%

“…The delocalized charge on the cationic head and/or the irradiation itself 37 can promote the electron transfer to generate the reduced form of the complex. ZnTPP at the interface may accept electrons from the complex or be activated directly by irradiation.…”

Section: Microemulsionsmentioning

confidence: 99%

Mechanistic aspects of photocatalytic activity of metalloporphyrin–titanium mixtures in microemulsions

et al. 2016

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Photocatalytic activity of titanium citrate and its water-in-oil microemulsions mix with zinc (II) tetraphenylporphyrin have been studied by means of adding 4-chlorophenol and following its degradation using artificial ultraviolet and visible light. 4-Chlorophenol is degraded in 71 and 86%, respectively, in 30 min with the generation of various intermediaries, whose possible formation mechanisms have been proposed based in the results of this research. The generation of benzene derivatives, different to those usually reported for this type of treatment, suggests the possibility of controlling the generation of intermediaries by simply changing the type of surfactant. In the case discussed here, we have derived a simple method for isomer generation of trimethylbenzene using a model organohalogenated compound as water contaminant and cetyltrimethylammonium bromide as surfactant.

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“…This problem may be solved using surfactant additives providing for the solubilization of hydrophobic substrates and an increased rate of nucleophilic substitution reactions, including alkaline hydrolysis. While the effect of monomeric surfactants on the rate of acyl group transfer reactions has been studied in considerable detail [3][4][5], the reactivity of nucleophilic reagents in the presence of gemini surfactant micelles has been studied much less extensively [2,6,7].In the present work, we studied the effect of new gemini surfactants I and II on the rate of alkaline hydrolysis of 4-nitrophenyl diethyl phosphonate (NPDEPS), which is a model analog of highly toxic organophosphorus pesticides and chemical warfare agents. The micellar effects of I and II are comparable to those for cetyltrimethylammonium bromide (CTAB), which is a monomeric surfactant.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Catalysis of the alkaline hydrolysis of 4-nitrophenyl diethyl phosphonate by cationic dimeric surfactant micelles

et al. 2011

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Dimeric (gemini) surfactants containing hydroxyl functional groups have been synthesized and studied. These new surfactants have low critical micelle formation concentrations (<5·10 -5 mol/L) and Krafft temperatures (£0°C). Depending on the pH of the medium, the alkaline hydrolysis of 4-nitrophenyl diethyl phosphonate, which is a model of organophosphorus ecotoxicants, proceeds 20-80 times more rapidly in the presence of gemini surfactant micelles than in water.The enormous interest in recent decades concerning the preparation and study of dimeric (gemini) surfactants and derived organized molecular systems has been due to the unique physicochemical characteristics of these compounds [1, 2], primarily, their anomalously low critical micelle concentrations (CMC » 10 -5 -10 -6 mol/L), which are one or two orders of magnitude less than for the corresponding monomeric surfactants, more efficient lowering of the surface tension of aqueous solutions, better solubilization of compounds with low solubility in water, and micelle polymorphism [2].Gemini surfactants may be seen as a promising basis for organized molecular systems corresponding to the requirements of "green chemistry" for the detoxification and utilization of toxic phosphorus acid esters [3]. The decomposition of ecotoxicants should be carried out under mild conditions using inexpensive and nontoxic solvents. Water is the preferred solvent from this viewpoint but most organophosphorus compounds have low aqueous solubility. This problem may be solved using surfactant additives providing for the solubilization of hydrophobic substrates and an increased rate of nucleophilic substitution reactions, including alkaline hydrolysis. While the effect of monomeric surfactants on the rate of acyl group transfer reactions has been studied in considerable detail [3][4][5], the reactivity of nucleophilic reagents in the presence of gemini surfactant micelles has been studied much less extensively [2,6,7].In the present work, we studied the effect of new gemini surfactants I and II on the rate of alkaline hydrolysis of 4-nitrophenyl diethyl phosphonate (NPDEPS), which is a model analog of highly toxic organophosphorus pesticides and chemical warfare agents. The micellar effects of I and II are comparable to those for cetyltrimethylammonium bromide (CTAB), which is a monomeric surfactant.New gemini surfactants I and II feature a bridging unit (spacer) functionalized by hydroxyl groups. Modification of the spacer by the introduction of hydroxyl groups improves the solubility of these compounds in water since gemini surfactants with the general formula m-s-m [2] have relatively high Krafft temperatures and low solubility in water, which hinders both the 108 0040-5760/11/4702-0108

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The dependence of micellar rate effects upon reaction mechanism

Cited by 111 publications

References 68 publications

Influence of colloid suspensions of humic acids on the alkaline hydrolysis of N‐methyl‐N‐nitroso‐p‐toluene sulfonamide

Influence of colloid suspensions of humic acids on the alkaline hydrolysis of N‐methyl‐N‐nitroso‐p‐toluene sulfonamide

Mechanistic aspects of photocatalytic activity of metalloporphyrin–titanium mixtures in microemulsions

Catalysis of the alkaline hydrolysis of 4-nitrophenyl diethyl phosphonate by cationic dimeric surfactant micelles

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